The major thrust of this Center proposal is to enable research investigators in systems neurobiology, neuroprosthesis designers and other electrophysiologists to communicate with excitable tissue using multichannel thin-film devices constructed on silicon substrates. One, two and three dimensional arrays with tens to hundreds of recording or stimulation sites can be custom designed to fit the needs of specific tissue communication applications. There is a significant service and technology transfer component to this center. The Center educates investigators on the technology and its use through a number of media. New users are first given stock devices found in a catalog published by the Center and proceed to working with the Center staff to design new probes and matching an interconnect technology to their application. The service component and the research projects of the Center are designed to move the technology in three major directions over the next five years: 1) make the design of probes more rational by developing a data base and models will quantitatively guide researchers and designers, 2) broaden the distribution offerings of the Center include fluid delivery probes, probes with active circuits, probes coated with bioactive materials and three dimensional probes and 3) move the fabrication from University Laboratories to commercial fabrication facilities. Three internal research projects drive these thrusts. These projects cover extensions of the device technology, through experimentation and modeling, understand more fully the recording and stimulation characteristics of the devices, and development of methods by which exact geometrical relationships between tissue and devices can be confirmed postmortem. In addition to these projects there are several collaborative projects with investigators in universities and industry involving all of our major application areas.